Role of microRNAs in Arsenic Stress Tolerance of Plants

Arsenic is a highly toxic carcinogenic element whose contamination in groundwater and soil has emerged as a problem of unprecedented scale in last few years. The arsenic exposure to humans occurs through drinking water and food and threatens to increase incidences of cancer and other ailments drastically in future. To safeguard people from arsenic through food, research has focused on understanding in depth mechanisms of arsenic stress responses in plants. These included laboratory-based and field studies and encompassed morphological, physiological, biochemical and molecular assays and also whole genome transcriptome and proteome analyses. These studies led to information about changes at biochemical and molecular levels which are reflected in morphological and growth changes. Further, the involvement of various signalling and regulatory elements has been revealed. Among these, microRNAs (miRNAs), which are 20-25 base pairs long RNAs, have emerged as important players in mediated arsenic stress responses in plants. miRNAs have been found to regulate signalling elements, transcription factors, hormones biosynthesis and responses, oxidative stress responses, sulphur metabolism etc. This review presents a discussion on miRNAs involvement in arsenic stress responses in plants and also sheds light on future perspectives.